1. Field of the Invention
The present invention relates to a teleconference system which makes it possible to hold an audio and video meeting between distant places connected by a communications network.
2. Description of the Prior Art
A prior-art equipment for a teleconference system is constructed by combining independent devices such as a display unit, a codec, a camera, a microphone and a console. In some cases, a document camera, an electronic blackboard and a small-sized computer are further combined in accordance with functions required for conferences.
Moreover, since such a prior-art teleconference equipment constructed by combining the independent devices is large in scale, a teleconference room for exclusive use is usually required for the teleconference. On the other hand, there is also an equipment for a teleconference system wherein fundamental devices are housed in a single rack so as to be movable, thereby dispensing with the need for a conference room for exclusive use.
In the teleconference system thus constructed, ordinarily still pictures and video can be exchanged between the terminals of the system.
Techniques relevant to the teleconference equipments are disclosed in the official gazettes of Japanese Patent Applications Laid-open No. 39790/1990 and No. 22989/1990.
In addition, Japanese Patent Applications concerning teleconference systems filed by the assignee of the present application are Patent Applications Laid-open Nos. 120889/1992 and 166884/1991, and Patent Applications Nos. 406984/1990, 25987/1991, 25991/1991, 174025/1991, 174046/1991, 174031/1991, 34009/1991 and 27086/1991.
Meanwhile, in the prior-art equipment for the teleconference system, the codec includes an A/D (analog-to-digital) converter and a D/A (digital-to-analog) converter for each of a still picture and video, and the still picture display and video display of a display unit are changed-over by switching a still picture signal and a motion picture signal which are delivered from the two D/A converters.
Alternatively, the simultaneous display of the still pictures and video is realized by delivering the still picture and motion picture signals to two separate display units, respectively.
With the method wherein the still picture display and the video display are changed-over, the conversation of the pertinent communicating terminal with the opposite terminal is not conveyed smoothly on account of a complicated switching operation, etc.
On the other hand, with the method wherein the still picture signal and the motion picture signal are respectively displayed on the separate display units, these two display units are necessitated to render the terminal equipment large in size. Besides, while the user of the equipment is watching the still picture, his/her eyes shift widely and are inevitably averted from the opposite communicating person.
It is therefore an object of the present invention to provide a teleconference equipment in which a still picture and video can be simultaneously displayed on a single display screen.
In the prior-art teleconference system, the teleconference room for exclusive use needs to be prepared as stated before, so that the introduction of the teleconference system involves a heavy financial burden. Moreover, when holding the teleconference, conferees must move to the teleconference room which is inconvenient.
In this regard, even the portable teleconference equipment needs to be moved by several people on account of the size and weight thereof and cannot be used with ease.
Because of such circumstances, there has been a great demand in recent years for the ability to hold a teleconference more conveniently and more readily.